1. Field of the Invention
The invention relates to multi-degree of freedom of motion rotary tool machines for machining hardware mounted on a rotatable tabletop and in particular to automatically evaluating the inclination and linear displacement alignment of the hardware centerline to a reference axis of rotation of the machine and calculating respective compensations for accurate machining.
2. Description of Related Art
Computer numerically controlled (CNC) machines are able to accurately machine and produce hardware with tolerances on the order of three one thousandths of an inch (0.003"). Methods and apparatuses are conventionally available to manually evaluate CNC machine component alignment. Automatic tool length compensation is also available to to compensate for tool lengths and diameters. Many CNC machines have rotatable tabletops for holding hardware during machining. Such machines are often used in automated workplaces where automated guide vehicles shuttle hardware mounted on pallets from machine to machine or to different machine cells for various machining operations such as in automated flexible manufacturing systems.
Conventionally, a piece of hardware is loaded in a fixture, for use on a pallet, and is moved into final position using a mallet and dial indicator. Positioning the hardware in the fixture in this manner is done to achieve a desired concentricity. This can sometimes require the loosening and resetting of the hardware. This method can not correct for inclinational errors observed as varying eccentricities at different heights on the hardware. In addition, the pallet registration system on multiple work stations in an automated flexible manufacturing system, can not be maintained to the consistency required for pallet interchangeability. Manual realignment of a set-up, each time it is assigned to a different work station, is not practical in this environment.
It is therefore highly desirable to have a machining technique that provides a way to automatically machine hardware that is loaded in a fixture without operator intervention to manually position the hardware.